| D074 | DMC | Direct Metal Casting | Process of making metal parts directly from a mold without intermediate steps. | Producing aluminum pump housings using direct metal casting. |
| D075 | DMF | Dimethylformamide | A solvent used in polymer processing and coatings. | Cleaning mechanical seals using DMF. |
| D076 | DMG | Deckel Maho Gildemeister | A well-known machine tool manufacturer. | CNC machining centers from DMG for precision parts. |
| D077 | DMM | Digital Multimeter | Electronic measuring tool for voltage, current, and resistance. | Checking motor winding resistance with a DMM. |
| D078 | DMP | Dimethyl Phthalate | A plasticizer for polymers to improve flexibility. | Adding DMP to PVC insulation for wiring in machines. |
| D079 | DMR | Design Modification Request | Formal request for engineering changes in design. | Submitting a DMR to change gear housing dimensions. |
| D080 | DMS | Design Management System | Software to track and control design documents. | Managing CAD files in a DMS for a turbine project. |
| D081 | DMT | Dimensional Measurement Tool | Devices for precision measurement of parts. | Using a DMT to check tolerances of crankshafts. |
| D082 | DMU | Design Mock-Up | A full-size model or digital representation of a design. | Reviewing a DMU before manufacturing engine components. |
| D083 | DN | Diameter Nominal | Nominal pipe size designation in piping systems. | Ordering DN50 pipe for a cooling water line. |
| D084 | DNB | Do Not Bend | Instruction to avoid bending critical components. | Labeling thin aluminum sheets with DNB for transport. |
| D085 | DNC | Direct Numerical Control | Computer system controlling multiple CNC machines. | Running multiple lathes via a central DNC system. |
| D086 | DND | Do Not Disturb | Tagging for sensitive mechanical operations in progress. | Placing DND signs during turbine balancing tests. |
| D087 | DNP | Do Not Polish | Instruction for surfaces needing rough texture. | Marking a cast surface with DNP to retain paint adhesion. |
| D088 | DNS | Dynamic Nozzle System | Adjustable nozzle design for fluid flow optimization. | Using a DNS in hydraulic testing. |
| D089 | DOA | Dead On Arrival | Equipment failure before first use. | Receiving a DOA hydraulic pump. |
| D090 | DOB | Date of Build | Manufacturing completion date. | Recording DOB on gearbox nameplates. |
| D091 | DOC | Depth of Cut | Amount of material removed in a machining pass. | Setting DOC to 2 mm for turning steel bars. |
| D092 | DOE | Design of Experiments | Statistical method to optimize processes. | Using DOE to refine welding parameters. |
| D093 | DOF | Degree of Freedom | Independent motion parameter in mechanical systems. | A robotic arm with 6 DOF for assembly work. |
| D094 | DOG | Dead Oil Gauge | Instrument for measuring static oil levels. | Checking gearbox oil with a DOG. |
| D095 | DOI | Degree of Inclination | Angle of slope for mechanical alignment. | Setting conveyor DOI to improve material flow. |
| D096 | DOL | Direct On Line | Motor starting method without soft-start. | Using DOL starter for a water pump motor. |
| D097 | DOM | Drawn Over Mandrel | Tube manufacturing process for precision steel tubes. | Using DOM tubing for hydraulic cylinders. |
| D098 | DON | Designated Operator Number | Unique ID for trained machine operators. | Assigning DONs in a factory safety program. |
| D099 | DOP | Dioctyl Phthalate | Plasticizer for increasing polymer flexibility. | DOP in rubber seals for hydraulic pumps. |
| D100 | DOS | Disk Operating System | Control software for CNC or legacy machines. | Operating old CNC mills running DOS. |
| D101 | DOT | Department of Transportation | Regulatory body for transport equipment. | Meeting DOT safety requirements for tank trucks. |
| D102 | DOV | Depth of Vacuum | Measurement of vacuum levels in systems. | Checking DOV in vacuum pumps. |
| D103 | DP | Differential Pressure | Pressure difference across a component. | Measuring DP across a filter in HVAC. |
| D104 | DPA | Dynamic Pressure Analysis | Measuring pressure fluctuations in systems. | Using DPA for turbine performance testing. |
| D105 | DPB | Differential Pressure Bypass | Valve allowing bypass when pressure exceeds limit. | Installing DPB valves in lubrication systems. |
| D106 | DPC | Differential Pressure Controller | Controls flow using pressure difference. | Using a DPC in hydraulic systems. |
| D107 | DPD | Differential Pressure Device | Measures or controls pressure difference. | Installing a DPD on heat exchangers. |
| D108 | DPE | Double Pipe Exchanger | Heat exchanger with one pipe inside another. | Using DPE for oil-to-water cooling. |
| D109 | DPF | Diesel Particulate Filter | Traps soot from diesel exhaust gases. | Installing a DPF in generator exhaust systems. |
| D110 | DPG | Differential Pressure Gauge | Displays pressure difference. | Monitoring filter clogging with a DPG. |
| D111 | DPH | Double Pitch Helix | Screw conveyor design with longer pitch. | Using DPH in bulk material handling. |
| D112 | DPI | Dots Per Inch | Printing resolution for mechanical drawings. | Printing CAD designs at 600 DPI. |
| D113 | DPK | Double Pipe Kiln | Rotary kiln with two concentric shells. | Using DPK for heat treatment processes. |
| D114 | DPL | Double Piston Lock | Safety lock for hydraulic systems. | Installing DPL in press machinery. |
| D115 | DPM | Defects Per Million | Quality metric in manufacturing. | Reducing defects from 3000 to 500 DPM. |
| D116 | DPN | Dead Point Neutral | Position where no torque is produced. | Adjusting crankshaft at DPN during timing. |
| D117 | DPO | Designated Process Owner | Person responsible for process quality. | Assigning DPO for machining line. |
| D118 | DPR | Design Progress Review | Periodic review of project design stages. | Conducting DPR for new pump design. |
| D119 | DPS | Differential Pressure Switch | Triggers action at preset pressure difference. | DPS shutting down pump on filter blockage. |
| D120 | DPT | Dye Penetrant Testing | Non-destructive testing for cracks. | Performing DPT on welded joints. |
| D121 | DPV | Double Port Valve | Valve with two inlet/outlet ports. | Using DPV for dual tank systems. |
| D122 | DPY | Double Ply | Material with two layers for strength. | Using DPY belts in conveyor systems. |
| D123 | DQ | Design Qualification | Ensuring design meets requirements. | Conducting DQ for a new boiler. |
| D124 | DR | Drawing Revision | Updated version of a design drawing. | Issuing DR after tolerance changes. |
| D125 | DRA | Dynamic Response Analysis | Evaluates system behavior under loads. | Running DRA on a suspension system. |
| D126 | DRB | Design Review Board | Panel overseeing engineering design. | Presenting to DRB for final approval. |
| D127 | DRC | Design Rule Check | Software check for design compliance. | Running DRC in CAD before production. |
| D128 | DRD | Design Requirements Document | Specifies all engineering requirements. | Preparing DRD for heat exchanger project. |
| D129 | DRF | Datum Reference Frame | Coordinate system for measurements. | Aligning part inspections to DRF. |
| D130 | DRM | Design Review Meeting | Meeting to evaluate design status. | Holding DRM for gearbox project. |
| D131 | DRN | Drain | Opening or fitting for fluid removal. | Installing DRN in hydraulic reservoir. |
| D132 | DRO | Digital Read-Out | Device displaying position on machine tools. | Using DRO for precision milling. |
| D133 | DRP | Disaster Recovery Plan | Plan for resuming operations after disruption. | Developing DRP for manufacturing plant. |
| D134 | DRR | Dynamic Range Ratio | Range of measurement capability. | Adjusting DRR of vibration sensors. |
| D135 | DRS | Dynamic Response Spectrum | Graph showing system response over frequency. | Using DRS in seismic analysis of machinery. |
| D136 | DRT | Design Review Team | Group reviewing mechanical designs. | Assigning DRT for engine upgrade project. |
| D137 | DRV | Drive | Component transferring motion or power. | Installing DRV in conveyor systems. |
| D138 | DRY | Drying | Process of removing moisture from materials. | DRY step in foundry sand preparation. |
| D139 | DS | Drive Shaft | Shaft transmitting torque between components. | Replacing DS in a truck transmission. |
| D140 | DSA | Dynamic Stability Analysis | Checking stability under varying loads. | Running DSA for bridge expansion joints. |
| D141 | DSB | Double Shear Block | Fixture for shear testing. | Using DSB to test rivets. |
| D142 | DSC | Differential Scanning Calorimetry | Measures heat flow in materials. | Using DSC for polymer characterization. |
| D143 | DSD | Detailed System Design | Final detailed engineering stage. | Completing DSD for HVAC plant. |
| D144 | DSE | Design for Serviceability and Economy | Engineering for cost-effective maintenance. | Applying DSE to pump design. |
| D145 | DSF | Dynamic Safety Factor | Safety margin in dynamic loading. | Using DSF for crane design. |
| D146 | DSG | Direct Shift Gearbox | Dual-clutch automated transmission. | DSG in high-performance cars. |
| D147 | DSH | Double Shoulder | Fastener design with two seating surfaces. | Using DSH bolts in turbine casings. |
| D148 | DSI | Direct Strength Indicator | Measures bolt preload directly. | Installing DSI washers in critical joints. |
| D149 | DSL | Double Seal | Mechanical seal with two sealing faces. | DSL in chemical pump applications. |
| D150 | DSM | Design Structure Matrix | Tool for analyzing system dependencies. | Using DSM in product architecture planning. |
| D151 | DSN | Design Serial Number | Unique identifier for a design. | Assigning DSN to prototype engines. |
| D152 | DSO | Designated Safety Officer | Person responsible for safety compliance. | Appointing DSO in a machine shop. |
| D153 | DSP | Digital Signal Processing | Processing of sensor and control signals. | DSP in vibration monitoring systems. |
| D154 | DSR | Design Safety Review | Review to ensure compliance with safety norms. | Conducting DSR for pressure vessel. |
| D155 | DSS | Decision Support System | Tool aiding engineering decision-making. | DSS for maintenance scheduling. |
| D156 | DST | Daylight Saving Time | Time adjustment affecting shift schedules. | Adjusting DST for plant operations. |
| D157 | DSU | Design Set-Up | Initial configuration of a system. | Performing DSU for CNC machining. |
| D158 | DSV | Double Shutoff Valve | Valve providing complete isolation. | DSV in steam lines for maintenance. |
| D159 | DSY | Dynamic System Yield | Output performance under dynamic loads. | Measuring DSY for shock absorbers. |
| D160 | DT | Downtime | Period when equipment is non-operational. | Tracking DT for a production line. |
| D161 | DTA | Dynamic Thermal Analysis | Measures material behavior under changing temperatures. | DTA of aerospace alloys. |
| D162 | DTB | Double Tube Bundle | Heat exchanger with two tube bundles. | Using DTB in refinery cooling systems. |
| D163 | DTC | Diagnostic Trouble Code | Error code from a machine’s ECU. | Reading DTC for hydraulic system fault. |
| D164 | DTD | Design-to-Delivery | Timeline from design start to product delivery. | Managing DTD for turbine parts. |
| D165 | DTE | Direct to Equipment | Supply line going directly to machinery. | Routing compressed air DTE for tools. |
| D166 | DTF | Design Test Fixture | Specialized fixture for testing components. | Building DTF for shock absorber testing. |
| D167 | DTG | Dye Tracer Gas | Used to detect leaks in systems. | Using DTG in heat exchanger leak tests. |
| D168 | DTH | Down-the-Hole | Drilling method with hammering near bit. | DTH drilling for geothermal wells. |
| D169 | DTI | Dial Test Indicator | Precision measurement device. | Using DTI to align lathe tailstock. |
| D170 | DTL | Detailed Technical Log | Comprehensive operation and maintenance record. | Maintaining DTL for gas turbines. |
| D171 | DTM | Digital Terrain Model | 3D representation of terrain for construction. | Using DTM for plant site planning. |
| D172 | DTN | Dynamic Torque Number | Torque measurement under motion. | Recording DTN for gear testing. |
| D173 | DTO | Design Transfer Order | Authorizes movement from design to production. | Issuing DTO for engine block casting. |
| D174 | DTP | Detailed Test Procedure | Step-by-step testing plan. | Preparing DTP for compressor testing. |
| D175 | DTR | Detailed Test Report | Document summarizing test results. | Completing DTR after pump performance test. |
| D176 | DTS | Data Transmission System | For communication in automation. | DTS connecting sensors to control units. |
| D177 | DTT | Dynamic Torsion Testing | Testing material resistance to twisting. | Conducting DTT for drive shafts. |
| D178 | DTU | Design Time Utilization | Efficiency metric for design resources. | Tracking DTU in R&D projects. |
| D179 | DTV | Disc Thickness Variation | Uneven wear in brake discs. | Measuring DTV in vehicle maintenance. |
| D180 | DTY | Drawn Textured Yarn | Yarn with improved mechanical properties. | DTY used in conveyor belts. |
| D181 | DU | Design Upgrade | Improving an existing design. | Implementing DU for higher pump efficiency. |
| D182 | DUA | Dual Action | Mechanism performing two actions. | Dual action hydraulic cylinder. |
| D183 | DUB | Double U-Bolt | Fastener with two U-shaped sections. | Using double U-bolts in pipe supports. |
| D184 | DUC | Ductile | Material property allowing deformation before fracture. | Ductile iron used in piping. |
| D185 | DUD | Dead Unload Device | Mechanism that unloads system when inactive. | Installing DUD in pneumatic systems. |
| D186 | DUE | Design Under Evaluation | In-progress design review status. | Marking component drawings as DUE. |
| D187 | DUF | Design Upgrade Factor | Ratio representing performance improvement. | Calculating DUF after pump redesign. |
| D188 | DUG | Double Universal Joint | Allows greater angular movement in shafts. | Using DUG in long drive shafts. |
| D189 | DUL | Design Usage Limit | Max load or stress a part can handle. | Defining DUL for crane hooks. |
| D190 | DUM | Dummy | Non-functional placeholder part. | Using a dummy gear in prototype assembly. |
| D191 | DUP | Duplicate | Copy of a part or document. | Making DUP of technical drawings. |
| D192 | DUR | Durability | Ability to withstand wear over time. | Testing material DUR in abrasion machine. |
| D193 | DUS | Dust Suppression | Methods to control airborne dust. | Installing DUS systems in foundries. |
| D194 | DUT | Device Under Test | Component currently being tested. | DUT in bearing fatigue testing. |
| D195 | DUV | Deep Ultra Violet | UV range used in material curing. | Using DUV lamps for adhesive curing. |
| D196 | DUW | Design Unit Weight | Weight per unit of design. | Calculating DUW for structural components. |
| D197 | DUX | Design User Experience | User interaction aspect of design. | Considering DUX for operator-friendly machinery. |
| D198 | DV | Design Validation | Confirming design meets needs. | Performing DV for pressure vessel safety. |
| D199 | DVC | Differential Valve Control | Valve operation based on pressure difference. | Using DVC in refrigeration systems. |
| D200 | DVL | Design Verification and Launch | Final design check before release. | Completing DVL before pump goes to market. |